Brake element



Patente Apr.

naa ELEMENT William Mann, Grosse Pointe, Mich., assigner to The BuddCompany, Philadelphia, Pa., a coinporation of Pennsylvania ApplicationAugust 31, 1944, Serial No. 552,131

4 Claims. i

The invention relates to a brake element having a lining of thecomposition type.

Such brake elements as composition brake shoes cooperating with anopposed rotary brake element are commonly comprised of a. metal (ci.iss- 251) -it is not subject to the deterioration of the rubbacking towhich the composition lining is secured. Some such composition liningsyare rel-A tures are developed in localized regions of ex cessively highpressure, which may result not only in producing heat checks in therotary brake elements, which are undesirable, but also increase the wearof the lining due both to the higher temperatures and the presence ofheat checks.

It has, heretofore, been proposedto equalize the pressure on the workingface of the lining by employing a rubber cushion between the lining andthe metal backing and this has eliminated these diiiiculties for themost part. However, the rubber cushion was likely to deteriorate in timedue to the high temperatures to which ltn was subjected in use, and alsodue to rapid change in temperature to which it was subjected in its useon vehicles, such as railroad trains, operating in regions where thenormal temperature ranged from below zero to over 100 Fahrenhelt and thebraking temperature between the lining and rotary brake element mightrise up to 800 or more. Furthermore, if the lining was not changedbefore it wore quite thin, this differential temperature effect on therubber was still more marked. To overcome these defects of the rubberbacking and at the same time retain its advantages, and provide stillother advantages, forms an object of the present invention.

This object is attained by a braker element or shoe having secured toits metal backing a lining varying in its characteristics from the-faceof the backing to the wear face of the lining, the layer of liningadjacent the shoe being relatively soft and yielding, while the layeradjacent the wear face being relatively hard and unyielding and havingsuperior braking and wear resisting qualities. The yielding layer actssimilarly to the rubber formerly used in distributing the brakingpressure evenly upon the wear face of the lining from the backing plate,at the same time ber due to the great and sudden changes of temperatureencountered in service. Yet more, the outer wear-resisting and harderlayer can be worn down further before requiring replacementwithoutaflectlng the cushioning layer of lining and braking may still behad'even if all `the `outer layer is worn down by braking on the moreyielding layer. Thus longer'tinle between re placement of theoutervlayer of the lining is made possible and this Without running thedanger of deleterlously affecting the cushioning inner layer adjacentthe backingk plate.

Furthermore. with this arrangement the' outer layer, when worn down, mayreadily be replaced by simply cementing a new layer to the unused partof the multilayer lining.

Other and further objects and advantages and the manner in which theyare attained will become clear from the following detailed descriptionwhen read in connection with the drawings y forming a part of thisspecification.

In the drawings:

Fig. 1 shows one manner of application of the brakeelement of theinvention, this view being aplan view of one-quarter of a railway truckhaving a brake applied to its wheel and axle assembly;

Fig. 2 is a. face view 'of a to the invention;

brake shoe according Fig. 3 is an edge View of the shoefwith partsbroken away to show a detail, and

Fig. 4 is a View similar to Fig. 3 showing a slight modification.

The invention has been` shown vapplied in Fig. 1 to a railway truckhaving a frame i0 spring supported from a wheel and axle assembly llthrough equalizer bars l2. The wheel and axle assembly carries a brakedisc I3 the opposite faces of which are engageabley by the spacedsegmental'shoes it which are carried from av support yoke l5 by leversi6 pivoted at Il, on

the support and between the ends of the levers opposite the ends thereofcarrying the shoes, and operative to press ment of the invention ismerely illustrative, for

the invention may be used in widely different brake embodiments.

As shown in Figs. 2 and 3, the shoe It compivotally connected to theshoes, k at i8. The actuating means for the levers may i comprise ai'luid pressure cylinder IS disposed prises the metal backing 20. ofarcuate form against one i'ace of which is secured a composition lining.In the embodiment shown. this lining is constituted of spacedkeystone-shaped blocks 2| extending across the width of the backfcemented, as indicated at 24, an outer layer 25 oi' composition liningmaterial.

l 'I'he lining material of the two layers differs in 4 bodiments shownand the invention may be applied in other relations without'departingfrom the main features thereof, and such changes and modifications areintended to be covered in the appended claims.

What is claimed is:

1. A brake element having a rigid metal backing, a composition brakelining secured to said backing and having braking effectiveness forsubstantially its entire thickness, and means securing said lining tothe backing, said lining having varying characteristics in the directionof its thickness. the portion of the lining adjacent the backing havingthe characteristic of being relatively soft and yielding and the portionof the lining adjacent the braking face having the charvacteristic ofbeing relatively hard and unyieldlng,

yieldabllity and hardness and preferably also,

differs in wear resisting qualities, the inner layer 23, for thepurposes of the invention, to enable it to serve as a cushioned supportfor the outer layer 25 from .the backing, being relatively soft andyielding in character. The outer layer 25,

on thev other hand, to enable it to resist wear, is'

relatively hard and unyielding in character. As shown, the two layersare substantially equal in thickness, but this particular thicknessrelation may -b'e changed without departing from the invention.

With this arrangement, it will be seen that the inner layer cushions theouter layer and allows it to adjust its wear lace to the: rotary brakeelement with substantially equal pressure throughout. At the same time,the yielding inner layer of composition lining is able to withstand theheat normally encountered in braking and may even itself become the wearface of the lining if the outer harder, wear resisting material is wornoft'. This makes it possible to wear down the outer layer 25 almost to,or to, the face of the inner layer before replacement and replacementcan be` eected by simply cementing a new layer in place on the remainderof the worn lining. At the same time, if the wear should proceed beyond'the outer layer before replacement was made, no harm would result,since the brakes would still be effective through the engagement of theinner layer with the rotary brake member.

According to the form shown in Fig. 4, the

inner and outer layers 26 and 21 may be molded,.`

if desired, in a single block,"28,'t'he inner vlamination of which hasthe soft and yielding character- 'istics similar to the block 23 of thepreferred form and the outer lamination 29 of which has the hard andunyielding characteristicsof the outer layer 25 of the preferred form.In this case theholes for receiving the rivets 22 will have to beextended to the braking face of the outer layer 21,

as shown, where rivets are used as the securing and said means securingthe lining to the backing terminating short of the outer i'ace of saidporprising a laminated structure including at least two laminae, onelamina next to thebacking being relatively soit and yielding and onenext to the braking face being relatively hard and wear-resisting, andsaid means securing the lining to the backing being associated solelywith said lamina next to the backing.

3. A brake element having a rigid metal backing, a nrst layerof'compositlon brake lining secured to said backing, means securing itto the backing of an extent from said backing materially less than thethickness of said layer and a second layer of composition brake liningcemented to said rst layer, the first layer being relatively soft andcompressible and the second said layer being relatively hard and lesscompressible than said rst layer.

4. A brake element having a rigid metal backing, a. composition brakelining koit substantial thickness secured thereto and having brakingei'- iectiveness forv substantially its entire thickness,

and means for securing said lining to the backing,

and said securing means for said lining termithe lining thickness.

REFERENCES CITED The following references are 'of record in the le ofthis patent:

UNrrED s'rA'rEs PATnNTs nating short of said half medium.

While several speciilc embodiments of the in- Number Name Date ventionhavevbeen shown and described and the 1,784,994 Morris -v Dec. 16, i930invention has been shown applied to a railway 2,158,337 Rasmussen May18,- 1939 brake, it will be understood that changes and 2,033,968 FetherMar. 17, 1936 modifications may be made in the speciilc em- 2,134,744Wales Nov. 1, 1938

